Electromagnetic coil



Oct. 4, 1960 H. R. HABEGGER ELECTROMAGNETIC COIL Filed Oct. 25, 1956 F/GZ ilk

INVENTOR. Herma/7 Hobegger BY Z/ the inner end of said coil.

United States Patent tiice 2,955,233 Patented Oct. 4, 1960 ELECTROMAGNETIC COIL Herman R. Habegger, Indianapolis, Ind., assignor to Cornell-Dubilier Electric Corporation, South Plainfield, NJ., a corporation of Delaware Filed Oct. 25, 1956, Ser. No. 618,285

Claims. (Cl. 317-158) This invention is concerned with a method and apparatus dealing with electromagnetic coils mounted on insulating material cores. More specifically, the invention deals with an electromagnetic coil that is to be used in a one wire circuit, i.e. a circuit in which one path thereof is carried by a framework including the coil support, or core, for the electromagnetic coil. It is an object of this invention to provide a unitary tab, or connector, that is adapted for quick insert-ion into place on an insulating material coil form or bobbin. The -tab as thus inserted, provides a contact element to which one end of the coil wire may be readily connected. Additionallythe coil, after it is wound, is ready to be merely pressed `into place on its core, whereupon electrical contact will be made between the core and the inner end of the coil to complete a ground circuit for one end of the coil.

Another object of the invention is to provide a method for assembling an electromagnetic coil on an insulating material, when being used in a grounded or one wire circuit. Such method provides for a rapid and simple operation involving manual or semi-manual winding and assembly of such a coil. This method eliminates a soldering operation for connecting one end of `au electromagnetic coil into the ground side of a one wire circuit. In addition, this method allows the inner end of the coil to be maintained completely out of the way since it is wound under, during subsequent winding operation. Y rBriey, .the invention includes a terminal connector for the inner end of an electromagnetic coil that is wound on an insulating material bobbin. The insulating material bobbin referred to is one having a centrally longitudinally perforated hub, with flanges at the ends thereof. The invention, in connection' with such a bobbin, comprises a conductive material member lying adjacent to the outer surface of said hub for electrically contacting This conductive material member also extends through one of 4the anges. The invention also comprises a second conductive material member lying along one side of said longitudinal perforation, and includes means for electrically connecting both said first and said second conductive members together in order to complete a low resistance electrical path therebetween. y

As to the method of this invention, it may be briefly de scribed as follows: A method of winding an electromagnetic coil on an insulating material bobbin for use in a one wire grounded circuit which comprises among others the step of. taking a bobbin having flanges at the ends of the hub thereof and also having an axial hole through the hub. The method further comprises the step of inserting a tab of conductive material through one of said flanges and into said hole, so that one end of said tab lies along the outer surface of said core and the other end lies along a side of said hole. Another step comprises. electrically connecting one end of some insulated wire to the end of said tab lying along the outer surface of said hub. A further step comprises winding said insulated wire on said bobbin around said hub for a predetermined number of turns. Another step comprises securing said coil winding to prevent accidental unwinding thereof; and a final step comprises providing for an electrical contact to be made with the outer end of said coil wire.

The foregoing and other objects and advantages of the invention will be more fully brought out in connection with the detailed description of the invention which follows, and which is illustrated in the drawings, in which:

Fig. l is an exploded perspective view showing a bobbin (with one flange broken away), a connector tab and a supporting core, indicating their relative positions when assembled;

Fig. 2 is a perspective view of a completed coil with wire wound on the bobbin, and indicating in an exploded manner the relationship of the connector tab therewith;

Fig. 3 is a plan view (somewhat enlarged) of a connector tab according to the invention;

Fig. 4 is a side elevation of the tab illustrated in Fig. 3;

Fig. 5 is an end elevation of the -tab illustrated in Figs. 3 and 4 and;

Fig. 6 is a transverse elevation, partially in cross sec? tion, taken across the hub of the bobbin, and illustrating the relative positions of the various elements when the bobbin and connector 4tab are in place yon an electro# magnetic core, or coil support.

Referring to all of the drawings in general, it is pointed out that a principal element of the invention is a unitary tab or connector 11 which is made up of three principal elements, as will be more fully explained below. An insulating material bobbin 12 may take various shapes and forms, but is here illustrated as having a generally rectangular cross section hub or core 13 that joins a pair of anges 14 and 15, one at each end thereof.

In Fig. 2 there is illustrated a completely wound electromagnetic coil 19 that surrounds the core 13 and is held in place `axially by means of the flanges 14 and 15 of the insulating material bobbin 12. It will be observed that the actual turns of insulated wire which go to make up the electromagnetic coil 19, are secured in place to prevent accidental unwinding thereof by means of any convenient tape, or like covering material 20. The outer end of the coil 19 is arranged for easy electrical contact therewith by means of a flexible external lead wire 21 having a tip 22 thereon, which is barecl of insulation and which may be tinned to provide easier and more lasting good contact properties.

In Fig. l there is illustrated a framework 26 which in this instance happens to be the frame for supporting a heavy duty vibrator. It will be clear that the coil and tab arrangement according to this invention, may be applied to a wide variety of different electrical mechanisms. Attached to the framework 26 in any convenient manner, such as by spot welding, there is an electromagnetic core or coil support 27. In this instance such coil support takes the form of a relatively wide flat tongue, which is bent out at right angles from a flat piece of support material 28. Support piece 28 is in turn fastened to an up standing back portion 29 of the framework 26, e.g. by spot welding as mentioned above. Thus, the coil support 27 is centrally located, extending horizontally outward from one end of the framework of the vibrator. The framework, including coil support 27, is constructed of a conductive material having desirable magnetic properties. In the particular vibrator framework 26, illustrated, it is constructed of steel having adequate magnetic perme- I' ability and good electrical conductivity.

. considerably larger.

axially through the hub 13 of the bobbin 12. Tab 11 al-so has an integral connecting portion 36 which extends across, transversely, at one end of the tab 11, joining the two sides V33 and 34 thereof, electrically as well as mechanically. The length of the connecting portion 36 is made substantially equal to the distance between one side of the hole 35, and the outside surface of the hub 13 extended.

The side 33 of tab` 11, has a necked in, or narrow portion 37. This aids in the connection of the inner end of the coil 19, since a Ibared end of the coil wire may be Wrapped once or twice around the side 33 -at this portion 37, and it will not slide off. This inner end of the coil Wire may then be soldered for insuring best electrical connection without sacrificing thev strength of the nonslip mechanical contact already made.

It will be observed that there are openings 39 through each of the fianges 14 and 15, lying generally parallel to the long sides of the hole 35. These openings 39 have dimensions such that the side 33 of the tab 11 fits easily through any one of the holes 39. Also the inner edge of each hole 39 is flush 'with the outer surface of the hub 13 of the bobbin.

Thus the tab 11 may be slid longitudinally into place on the bobbin 12, so that the tab 11 lies with its shorter and narrower side 33 along the outer surface of the hub 13, while the other side 34 of the tab 11 lies close to one side of the axial perforation or hole 35 through the hub 13. After the tab 11 has been positioned on the bobbin 12, the bobbin may be placed in its nal position over the core or coil support 27, following the winding of a coil on the bobbin. In this manner a good electrical connection is had between the side 34 of the tab 11 and one side or surface of the electromagnetic core or coil support 27. This mechanical pressure contact is aided in providing good electrical contact, by reason of a pair of ridges or surface deformations 42 and 43, which have been stamped out or otherwise formed in the side 34. Consequently, the raised portions of these ridges 42 and 43 will create localized high pressure contact with the surface of the coil support 27. This is best illustrated in the cross section view of Fig. 6, where the bobbin 12 is shown in place on the coil support 27 with the tab 11 also in place on the bobbin, without any showing of the coil. In this showing the tab 11 is in place on rthe other side of the core 27 from that indicated in the exploded showing of Fig. l.

It is pointed out that the purpose for having four of the openings 39 instead of only one of the same, is to make Ifor greater simplicity during the process of assembly of a coil employing a tab in accordance with the invention. Thus by employing four such openings 39, the bobbin 12 need not be shifted or rotated in any manner from the attitude which it assumes when first picked up, and the tab 11 may be inserted with its smaller side 33 passing through an opening 39, with a minimum of movement as to bobbin positioning, or movement of the tab relative to the bobbin.

The method which this invention contemplates is one for winding an electromagnetic coil on an insulating material bobbin, which coil is to be employed in a one wire circuit. The steps involved in this method will become' entirely clear by reference to the drawings where applicable. The method will be described in terms of a manual operation;v however, individual steps, or even the whole process might be carried out Iby machine without altering the process according to the invention.

As a first step in the process. of winding a coil in accordance with this invention, an operator must/take a bobbin 12 made of insulating material which has anges 14, 15 extending from a hub 13, which hub in tum has an axial passage or hole 35 therethrough. Next the operator will insert a tab 11 thereon. Such tab will be. constructed of a conductive material, and will be inserted with one side 34 thereof lying along an edge of the axial hole 35 through t-he hub 13 of the bobbin 12. At the same time, the other side 33 of the tab 11 will be inserted through a passageway or opening 39 that lies substantially flush with the surface of the hub 13 of the bobbin 12. The final resting place `for the tab 11 will leave one side 33 exposed for ready access thereto, along the outer surface of the hub 13.

1The next step is 4to make an electrical connection between the side 33 of the tab 11 thus exposed, and one end of an insulated wire that is to be wound on the bobbin to form an electromagnetic coil 19. Such connection may `be merely a mechanical contact between a bared end of the insulated coil wire and the narrow portion of the exposed side 33 of the tab 11, eg. by wrapping a turn or so of the bared coil wire around this side of the tab at the narrow part. However, to insure a corrosion resisting contact, the coil wire should also be soldered to the tab 11 in addition to the wrapped turns, as is usual with such electrical connections,

Next the operator will wind the insulated wire on thebobbin 12, around the hub 13 thereof, until the desired `number of turns has been completed.

Then another step is to secure the wire of the wound coil 19 in place to avoid accidental unwinding.

Still another step (which may be eliminated in some instances) is that of providing for a exible connector 21 that makes for easy electrical contact with the outer end of the electromagnetic coil 19.

A final step is that of placing the completed coil -19 with its tab 11 in place thereon, over a coil support 27. The coil support, or core 27, must be made of conduc-v tive material and may in addition be electromagnetic material, so as to form a highly permeable core for the coil 19. This final step might be carried out manually in some instances. However, a mechanical press most likely will `be employed to snugly position the completed coil 19 and its tab 11 over the coil support 27, for completing good electrical contact between the tab and the coil support.

While certain embodiments of the invention have been described herein in some detail, in accordance with the applicable statutes, this is not to be taken as limiting the invention in any manner, but merely as being descriptive thereof.

l It is claimed:

l. A terminal connector for the inner end of an electromagnetic coil wound on lan insulating material bob-V bin havingy a central longitudinally perforated hub with` perpendicularly disposed extending flanges at the ends thereof comprising a first conductive material portion lying adjacent to the outer surface of said hub for making electrical contact with the inner end of said coil and extending through one of said flanges, a second conductive material portion lying along one side of said longitudinal perforation within said hub and disposed substantially parallel to said first conductive portion, and a third conductive material portion disposed adjacent the external surface of said fiange electrically interconnecting said first and second conductive portions to complete a low resistance electrical path therebetween.

2. A terminal connector for the inner end of an electromagnetic coil `wound on an insulating material bobbin having a central longitudinally perforated hub with perpendicularly disposed extending flanges at the ends thereof comprising a first conductive material portion lying adjacent to the outer surface of said hub for electrically contacting the inner end of said coil and extending through one of said flanges, a second conductive material portion lying along one side of said longitudinal perforation Within said hu-b and disposed substantially parallel to said first portion, said second portion having deformable extendedsurfaces thereon to increase the effective thickness thereof, and a third conductive material portion for electrically interconnecting said first and second conductive portions adjacent the external surface of said flange in order to complete a low resistance electrical path therebetween.

3. An electromagnetic coil assembly for removable mounting upon a coil support member comprising an insulating material bobbin having perpendicularly disposed iirst and second extending anges disposed at the ends of a hollow hub, a length of conducting wire convolutely wound about said hub and positioned intermediate Isaid ilanges, said length of wire having its inner end disposed adjacent said hub surface intermediate said anges land a connector for the inner end of said wire including a first conductive material portion extending through said first flange and disposed adjacent the outer surface of said bobbin hub for connection to the inner end of said length of wire, a second conductive material portion disposed within said hollow hub for electrical connection to said coil support member insertable therein and extending beyond said -rst flange and a third conductive material portion disposed externally adjacent t-he surface of said first ange electrically interconnecting the extending portions of said first and second conductive material portions of said connector to complete a low resistance path therebetween.

4. An electromagnetic coil assembly for removable mounting upon a coil support member comprising an insulating material bobbin having perpendicularly disposed extending anges disposed at the ends of a hub having an axial passage therethrough, at least one of said flanges having an opening therethrough disposed substantially flush with the outer surface of said hub, a

length of conduct-ing wire convolutely wound about said hub and positioned intermediate said anges, said length of wire having its inner end disposed adjacent said hub surface intermediate said flanges and a U-shaped connector `for the inner end of said wire including a first conductive portion extending through said opening in said ange and disposed adjacent the outer surface of said bobbin hub for connection to the inner end of said length of wire, a second conductive portion disposed within said axial passage for connection to said coil support member insertable therein and a third conductive portion disposed externally adjacent said apertured ange for electrically interconnecting said first and second conductive portions.

5. The electromagnetic coil assembly as set forth in claim 4 wherein said second conductive portion of said U-shaped connector has deformed extended surfaces thereon to increase the etective thickness thereof and to provide for a compressive engagement between said second portion and said insertable coil support member.

References Cited in the ile of this patent UNITED STATES PATENTS 1,813,154 Franz July 7, 1931 1,950,156 Swoboda Mar. 6, 1934 2,445,587 Sims July 20, 1948 2,497,484 Wood Feb. 14, 1950 2,628,996 Mayo Feb. 17, 1953 2,691,811 Wagar Oct. 19, 1954 

